Techniques of generating the optimal travel locus of a vehicle and offering various kinds of driving support or performing automatic driving using the travel locus have been developed. Patent Citation 1 discloses a device that detects the road shape in front of a vehicle, calculates the future position of the vehicle on the basis of the road shape and the travel speed of the vehicle, and projects and displays the future position of the vehicle on a windshield. Particularly in the case of a curved road, a clipping point, which is a characteristic point of curved roads, and the future position of the vehicle are projected and displayed together on the windshield. In addition, a method of generating an optimal travel locus for traveling at the maximum speed on a curved road is disclosed in Non-patent Citation 1.